U.S. patent number 11,204,266 [Application Number 16/727,070] was granted by the patent office on 2021-12-21 for sensor module and protective glass.
This patent grant is currently assigned to AGC INC.. The grantee listed for this patent is AGC INC.. Invention is credited to Shusaku Akiba, Satoshi Kanasugi, Satoshi Ogami, Masao Ozeki, Satoshi Takeda.
United States Patent |
11,204,266 |
Akiba , et al. |
December 21, 2021 |
Sensor module and protective glass
Abstract
A sensor module includes: a base member; at least one of a
single or a plurality of sensors and vibrators arranged on the base
member; and a protective member constituted of at least one flat
surface or a curved surface, provided so as to cover the at least
one of the sensors and the vibrators. A part or whole of the
protective member is formed of a strengthened glass and the
strengthened glass is a chemically strengthened glass or a
physically strengthened glass.
Inventors: |
Akiba; Shusaku (Tokyo,
JP), Ozeki; Masao (Tokyo, JP), Takeda;
Satoshi (Tokyo, JP), Kanasugi; Satoshi (Tokyo,
JP), Ogami; Satoshi (Tokyo, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
AGC INC. |
Chiyoda-ku |
N/A |
JP |
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Assignee: |
AGC INC. (Chiyoda-ku,
JP)
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Family
ID: |
1000006005778 |
Appl.
No.: |
16/727,070 |
Filed: |
December 26, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200132521 A1 |
Apr 30, 2020 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2018/025402 |
Jul 4, 2018 |
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Foreign Application Priority Data
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Jul 5, 2017 [JP] |
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JP2017-132137 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01D
11/245 (20130101); B32B 17/10137 (20130101); G01D
11/26 (20130101) |
Current International
Class: |
G01D
11/26 (20060101); B32B 17/10 (20060101); G01D
11/24 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2006-203563 |
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Aug 2006 |
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JP |
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2006-206283 |
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Aug 2006 |
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JP |
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2006206283 |
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Aug 2006 |
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JP |
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2007-174323 |
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Jul 2007 |
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JP |
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2008-288720 |
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Nov 2008 |
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JP |
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2009-4866 |
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Jan 2009 |
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JP |
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2009-10906 |
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Jan 2009 |
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JP |
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2012-148909 |
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Aug 2012 |
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JP |
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2015-125022 |
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Jul 2015 |
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JP |
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2016-121051 |
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Jul 2016 |
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JP |
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2016-531792 |
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Oct 2016 |
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JP |
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2016-538233 |
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Dec 2016 |
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JP |
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WO 2013/047679 |
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Apr 2013 |
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WO |
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Other References
International Search Report dated Sep. 25, 2018 in
PCT/JP2018/025402 filed Jul. 4, 2018, citing documents AG-AJ and
AP-AX therein, 2 pages. cited by applicant .
"Safety Glass Processing Tochnology", edited by Engineering Glass
Division of CSG Group, pp. 25-26, Guangzhou: South China University
of Technology Press, Mar. 31, 2010 (with machine transtation).
cited by applicant .
"Technical Specification for Glass Curtain Wall Engineering",
edited by Chen Jiandong, pp. 172-173, Beijing: China Construction
Industry Press, Dec. 31, 1996 (with machine translation). cited by
applicant .
"Notes for Mechanical Manufacturing Inspectors", edited by the
Quality and Safety Supervision Division of the National Machinery
Industry Council, p. 149, Beijing: Machinery Industry Press, Sep.
30, 1990 (with machine translation). cited by applicant.
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Primary Examiner: Williams; Jamel E
Attorney, Agent or Firm: Oblon, McClelland, Maier &
Neustadt, L.L.P.
Claims
The invention claimed is:
1. A sensor module comprising: a base member; at least one of a
single or a plurality of sensors and vibrators arranged on the base
member; and a protective member constituted of at least one flat
surface or a curved surface, provided so as to cover the at least
one of the sensors and the vibrators, wherein a part or whole of
the protective member is formed of a strengthened glass, wherein
the strengthened glass is a chemically strengthened glass, has a
thickness of from 1.5 mm to 3.5 mm, and has a depth of compressive
stress layer in a range of from 200 .mu.m to 580 .mu.m, the
chemically strengthened glass has a curved surface shape having a
convex surface and a concave surface, and a value obtained by
subtracting a surface compressive stress value of the concave
surface from a surface compressive stress value of the convex
surface is 10 MPa or more.
2. The sensor module according to claim 1, wherein the strengthened
glass has a surface compressive stress value of 400 MPa or
more.
3. The sensor module according to claim 2, wherein the strengthened
glass has the surface compressive stress value of 600 MPa or
more.
4. The sensor module according to claim 1, wherein the chemically
strengthened glass has a surface compressive stress value of 700
MPa or more.
5. The sensor module according to claim 1, wherein the chemically
strengthened glass has the depth of the compressive stress layer in
a range of from 250 .mu.m to 580 .mu.m, and has a compressive
stress value at a depth of 100 .mu.m from a surface of 100 MPa or
more.
6. The sensor module according to claim 1, wherein a value obtained
by subtracting a depth of compressive stress layer of the concave
surface from a depth of compressive stress layer of the convex
surface is 10 .mu.m or more.
7. A sensor module comprising: a base member; at least one of a
single or a plurality of sensors and vibrators arranged on the base
member; and a protective member constituted of at least one flat
surface or a curved surface, provided so as to cover the at least
one of the sensors and the vibrators, wherein a part or whole of
the protective member is formed of a strengthened glass, and the
strengthened glass is a chemically strengthened glass, wherein the
chemically strengthened glass has at least one bending point in a
region forming the compressive stress layer and has a stress
distribution curve having a different inclination with the bending
point as a boundary.
8. The sensor module according to claim 1, wherein the vibrator an
ultrasonic generating element.
9. The sensor module according to claim 1, wherein the protective
member has a transparent heater.
10. A sensor module comprising: a base member; at least one of a
single or a plurality of sensors and vibrators arranged on the base
member; and a protective member constituted of at least one flat
surface or a curved surface, provided so as to cover the at least
one of the sensors and the vibrators, wherein a part or whole of
the protective member is formed of a strengthened glass, and the
strengthened glass is a chemically strengthened glass or a
physically strengthened glass, wherein the strengthened glass has a
first main surface and a second main surface facing the first main
surface, and has an end surface between the first main surface and
the second main surface, and the end surface has a surface
roughness in a range of from 0.01 .mu.m to 1.0 .mu.m.
11. The sensor module according to claim 1, wherein the
strengthened glass is a glass ceramics.
12. The sensor module according to claim 1, wherein the
strengthened glass has a water-repellent film on the surface of the
strengthened glass.
13. A protective glass constituted of a flat surface or a curved
surface, wherein a part or whole of the protective glass is a
strengthened glass, wherein the strengthened glass is a chemically
strengthened glass, has a thickness of from 1.5 mm to 3.5 mm, and
has a depth of compressive stress layer in a range of from 200
.mu.m to 580 .mu.m, the chemically strengthened glass has a curved
surface shape having a convex surface and a concave surface, and a
value obtained by subtracting a surface compressive stress value of
the concave surface from a surface compressive stress value of the
convex surface is 10 MPa or more.
14. The protective glass according to claim 13, having an
ultrasonic vibrator.
15. The protective glass according to claim 13, having a
transparent heater.
Description
TECHNICAL FIELD
The present invention relates to a sensor module accommodating
therein at least one of a sensor and a vibrator, and a protective
glass protecting a sensor or a vibrator.
BACKGROUND ART
A plurality of sensors having various functions are mounted on a
car, an electric train, a mobile equipment such as drone, and a
security device such as an outdoor sensor or a surveillance camera.
A sensor module using a resin cover as a protective member
protecting those sensors is known. When a sensor is arranged
outdoors, it is required to select a material strong to weathering
and heat shock, in addition to rigidity and scratch resistance of a
protective member protecting a sensor.
The kind of the sensor arranged inside the protective member is an
important factor for selecting a structure and material of the
protective member. Uses of a sensor may be impaired depending on
the structure and material of the protective member. For example,
as a protective glass protecting the sensor, it is required to
select a material having high transmitting property that transmits
visible light.
A sensor using ultrasonic waves is known as a sensor that is
mounted on a surveillance camera and a car (Patent Literature 1).
The ultrasonic sensor described in Patent Literature 1 can receive
ultrasonic waves that was sent from a transmitter element
transmitting ultrasonic waves and reflected by an object to be
detected, by a receiving member having a receiving part receiving
ultrasonic wave.
Furthermore, ultrasonic waves are utilized in water repellency and
cleaning of a window in addition to the measurement of a distance
(Patent Literature 2). It can be expected that uses of the sensor
using ultrasonic waves will be further expanded in future.
As a structure having a sensor arranged inside the protective
member, a structure having a sensor arranged inside a protective
member using a resin is known (Patent Literature 3). Patent
Literature 3 discloses that electric continuity with electrodes of
a vibrator arranged inside a casing is secured while using a resin
casing as a protective member accommodating an ultrasonic
sensor.
CITATION LIST
Patent Literature
Patent Literature 1: JP-A-2007-174323
Patent Literature 2: JP-T-2016-531792 (the term "JP-T" as used
herein means a published Japanese translation of a PCT patent
application)
Patent Literature 3: JP-A-2006-203563
SUMMARY OF INVENTION
Technical Problem
However, the protective member using a resin described in Patent
Literature 3 had a problem that when the protective member was
arranged outdoors, the protective member has low rigidity and does
not have excellent scratch resistance and weather resistance.
The present invention has been completed in view of the above and
has an object to provide a sensor module having higher rigidity as
compared with the case of using a resin as a protective member and
having excellent scratch resistance and weather resistance, by
using a chemically strengthened glass as a protective member.
Solution to Problem
According to a certain aspect of the present invention, a sensor
module including: a base member; at least one of a single or a
plurality of sensors and vibrators arranged on the base member; and
a protective member constituted of at least one flat surface or a
curved surface, provided so as to cover the at least one of the
sensors and the vibrators, wherein a part or whole of the
protective member is formed of a strengthened glass and the
strengthened glass is a chemically strengthened glass or a
physically strengthened glass, is provided.
According to a certain aspect of the present invention, the sensor
module, wherein the strengthened glass has a surface compressive
stress value of 400 MPa or more and a depth of compressive stress
layer of 10 .mu.m or more, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass has the surface compressive
stress value of 600 MPa or more and the depth of compressive stress
layer of 40 .mu.m or more, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass is a chemically strengthened
glass and has a thickness of from 0.5 mm to 3.5 mm, is
provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass is a chemically strengthened
glass, has a thickness of from 1.5 mm to 3.5 mm, and has a depth of
compressive stress layer in a range of from 200 .mu.m to 580 .mu.m,
is provided.
According to a certain aspect of the present invention, the sensor
module, wherein the chemically strengthened glass has a surface
compressive stress value of 700 MPa or more, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the chemically strengthened glass has the depth of
the compressive stress layer in a range of from 250 .mu.m to 580
.mu.m, and has a compressive stress value at a depth of 100 .mu.m
from a surface of 100 MPa or more, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the chemically strengthened glass has a curved
surface shape having a convex surface and a concave surface, and a
value obtained by subtracting a surface compressive stress value of
the concave surface from a surface compressive stress value of the
convex surface is 10 MPa or more, is provided.
According a certain aspect of the present invention, the sensor
module, wherein a value obtained by subtracting a depth of
compressive stress layer of the concave surface from a depth of
compressive stress layer of the convex surface is 10 .mu.m or more,
is 10 .mu.m or more is provided.
According a certain aspect of the present invention, the sensor
module wherein the chemically strengthened glass has at least one
bending point in a region forming the compressive stress layer and
has a stress distribution curve having a different inclination with
the bending point as a boundary, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the vibrator has an ultrasonic generating element,
is provided.
According a certain aspect of the present invention, the sensor
module, wherein the protective member has a transparent heater, is
provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass has a first main surface and
a second main surface facing the first main surface, and has an end
surface between the first main surface and the second main surface,
and the end surface has a surface roughness in a range of from 0.01
.mu.m to 1.0 .mu.m, is provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass is glass a ceramics, is
provided.
According a certain aspect of the present invention, the sensor
module, wherein the strengthened glass has a water-repellent film
on the surface of the strengthened glass, is provided.
According a certain aspect of the present invention, a protective
glass constituted of a flat surface or a curved surface, wherein a
part or whole of the protective glass is a strengthened glass, and
the strengthened glass is a chemically strengthened glass or a
physically strengthened glass, is provided.
According a certain aspect of the present invention, the protective
glass having an ultrasonic vibrator is provided.
According a certain aspect of the present invention, the protective
glass having a transparent heater is provided.
Advantageous Effects of Invention
The sensor module of the present invention uses a strengthened
glass as a protective member and therefore has high surface
strength and edge strength, has high rigidity and scratch
resistance and further has high weather resistance (weathering
resistance and heat shock resistance). Therefore, the sensor module
is suitable for arranging outdoors.
BRIEF DESCRIPTION OF DRAWINGS
(a) to (c) of FIG. 1 are perspective views showing one example of
the configuration of a sensor module in the embodiment of the
present invention.
FIG. 2 is a side view showing one example of the configuration of a
mounting part in this embodiment.
(a) and (b) of FIG. 3 are perspective views showing one example of
a power supply mechanism of the mounting part in this embodiment.
(a) of FIG. 3 shows a wired power supply and (b) of FIG. 3 shows a
wireless power supply.
(a) and (b) of FIG. 4 are perspective views showing one example of
the arrangement of a vibrator or a transparent heater in this
embodiment.
DESCRIPTION OF EMBODIMENTS
Preferred embodiment of the present invention is described by
reference to the drawings. In the description of reference signs in
the drawings, the same or corresponding reference signs are
allotted to the same or corresponding members or parts, and
duplicate descriptions are omitted.
Furthermore, the expression "from . . . to" showing a numerical
range in the present description is used in the meaning of
including the numerical values indicated before and after "to" as
the lower limit and the upper limit.
<Sensor Module>
The sensor module of this embodiment includes a base member 15, at
least one of a single or a plurality of sensors 20 and vibrators 40
arranged on the base member 15, and a protective member 1
constituted of at least one of a flat surface and a curved surface,
provided so as to cover the at least one of the sensor 20 and the
vibrator 40. The elements constituting the sensor module of this
embodiment are described in detail below.
<Protective Member 1>
(a) and (b) of FIG. 1 are perspective views showing one example of
the configuration of a protective member 1 in this embodiment. (a)
of FIG. 1 is a structure using a protective glass 10 as a lid part
of a cylindrical casing (protective member 1) accommodating a
sensor 20. (b) of FIG. 1 is a structure using a glass as a
spherical surface of a hemisphere accommodating the sensor 20. A
part or the whole of the protective member 1 is formed using the
protective glass 10, but a support part 2 supporting the protective
glass 10 may be formed in a part of the protective member 1 as
shown in (a) of FIG. 1. The support part 2 may be a glass, but a
metal such as stainless steel or alumite may be used. The
protective member 1 is not limited to a cylindrical shape or a
hemisphere, and may be a columnar shape, a prismatic shape and a
three-dimensional shape such as a spherical regular polyhedron ((c)
of FIG. 1). The protective member 1 can be formed by laminating a
plurality of glasses. In the case of forming the support part 2, an
adhesive layer is formed between the support part 2 and the
protective glass 10, thereby sticking the support part 2 to the
protective glass 10.
The protective member 1 accommodates the sensor 20 having detecting
function or sensing function using millimeter wave, ultrasonic
wave, visible light, infrared light or LIDAR or comprehensively
using those. In the case where the sensor module of this embodiment
is arranged outdoors, the protective member 1 as a casing is
required to protect the mounting part 5 from climatic factors such
as rain and snow and external factors such as shock by stepping
stone. Therefore the protective member 1 requires certain strength
against those factors.
The adhesive layer (not shown) sticking the protective glass 10 to
the support part 2 preferably contains at least one selected from
the group consisting of a polyvinyl acetate resin, a polyvinyl
chloride resin, a polyvinyl alcohol resin, an ethylene copolymer
resin, a polyacrylic acid ester resin, a cyanoacrylate resin, a
saturated polyester resin, a polyamide resin, a linear polyimide
resin, a melamine resin, a urea resin, a phenol resin, an epoxy
resin, a polyurethane resin, an unsaturated polyester resin, a
reactive acrylic resin, a rubber resin, a silicone resin, a
modified silicone resin, a glass frit and a solder. By forming an
adhesive layer made of a material that does not deform and does not
weather even though arranged outdoors, using the resins and the
like described above, durability of the protective member 1 can be
enhanced.
When the protective member 1 has a transparent heater 60, the
protective member can exhibit functions of anti-fogging and snow
melting and can prevent that the sensor does not work by fogging
and snow. Thus, this is preferred (see (a) of FIG. 4 and (b) of
FIG. 4). The transparent heater is, for example, a transparent
electrode of ITO or the like deposited at a sensor side of the
protective member 1, and an electric current is applied to the
transparent electrode, thereby generating heat. Water droplets and
snow are evaporated by the heat, and water droplets and snow can be
removed from the surface of the protective member 1. In order to
exhibit the similar functions, a non-transparent metal may be used
as a heater. In this case, the portion other than a window used for
the sensor may be covered with the non-transparent metal, and the
metal may be functioned as a heater.
<Protective Glass 10>
The protective glass 10 can be formed by subjecting a glass
obtained through each step of cutting a large-sized plate glass
into small size, followed by machining and polishing, and
subjecting strengthening treatment such as chemical strengthening
or physical strengthening. As the cutting method of the plate
glass, for example, cutting by diamond blade, or a scribe cleaving
method, a laser cutting method and the like can be applied. In case
where strength of the protective glass 10 desired to be increased,
a surface layer part of the protective glass 10 is preferably
chemically strengthened or physically strengthened, and more
preferably all of the surface layer part is chemically strengthened
or physically strengthened. As a tool for applying machining or
polishing to the protective glass, whetstone can be used. Other
than this, a buff, a brush and the like formed of cloth, leather,
rubber or the like can be used. In this case, an abrasive such as
cerium oxide, alumina, carborundum or colloidal silica can be used.
Above all, whetstone is preferably used as a polishing tool from
the standpoint of dimensional stability.
In the protective glass 10, adhesiveness between the support part 2
and the mounting part 5 is improved by roughening the portion
contacting the support part 2 or the mounting part 5 (for example,
the portion corresponding to the end surface of the protective
glass). The shape of the protective glass 10 is not particularly
limited so long as the protective glass has a first main surface, a
second main surface facing the first main surface and an end
surface between the first main surface and the second main surface.
For example, in the case where the protective glass 10 as a
hemisphere shown in (b) of FIG. 1 is viewed from the side of a
concave surface, when the portion (end surface) drawing a circle
with a predetermined width is roughened, adhesiveness between the
surface showing the circle and the facing portion to be bonded is
improved, thereby facilitating the fixation. As a result, the
protective glass 10 can be stably mounted. The level of roughening
is specifically that a surface roughness Ra is 0.01 .mu.m or more,
preferably 0.05 .mu.m or more, more preferably 0.1 .mu.m or more
and still more preferably 0.2 or more. When the end surface is
excessively roughened, the adhesiveness between the end surface and
the facing portion may be impaired. Therefore, surface roughness Ra
of the end surface is 1.0 .mu.m or less, preferably 0.5 .mu.m or
less and more preferably 0.4 .mu.m or less. In the case where the
support part 2 is constituted of a strengthened glass, the surface
roughness Ra of the end surface of the support part 2 is preferably
within the above range. The surface roughness Ra in the present
description means arithmetic mean roughness defined in JIS
B0601:2001.
The protective glass is not limited to the hemispherical protective
glass 10 represented by (b) of FIG. 1. Other than a hemisphere,
when a dome-shaped protective glass having a curved surface shape
is used, in the case where the sensor 20 is a camera for visible
light, the protective glass has the effect of expanding an imaging
range (a field of view), which is preferred. In the case where the
protective glass has a dome shape (curved surface shape), its size
is not particularly limited. For example, an outer diameter is a
range of from 10 to 30 mm and an inner diameter is a range of from
5 to 30 mm. When a dome-shaped glass plate including a hemisphere
is processed to a dome shape and then subjected to a chemical
strengthening treatment, large surface compressive stress is
obtained at the side of a convex surface of the chemically
strengthened glass plate as compared with the side of a concave
surface thereof by shape effect. Furthermore, in the chemically
strengthened glass plate, large depth of a compressive stress layer
is obtained at the side of a convex surface as compared with the
side of a concave surface thereof. For this reason, when the
protective glass is particularly placed in outdoor environment,
larger strengthening is obtained at the side of a convex surface
corresponding to the side of a front surface, and this is
preferred. The dome-shaped glass plate can realize desired surface
compressive stress and depth of a compressive stress layer by
appropriately adjusting the conditions of the chemical
strengthening treatment.
In particular, in the case of chemically strengthening a
dome-shaped glass plate, a value obtained by subtracting a surface
compressive stress value of a concave surface from a surface
compressive stress value of a convex surface is preferably 10 MPa
or more, more preferably 15 MPa or more and still more preferably
20 MPa or more. Furthermore, a value obtained by subtracting DOL of
a concave surface from DOL of a convex surface is preferably 10
.mu.m or more, more preferably 20 .mu.m or more and still more
preferably 40 .mu.m or more.
The dome-shaped protective glass 10 can be obtained by, for
example, bending. Preferred embodiment of the bending is described
below, but a method for obtaining a curved surface shape protective
glass 10 in this embodiment is not limited to the embodiment
described below.
In the bending, a glass is placed on a mold constituted of carbon,
heated to a temperature region of from 600 to 950.degree. C.,
hot-pressed for from 30 to 180 seconds while maintaining the
temperature, and then gradually cooled. Thus, a curved surface
shape glass plate is formed. The curved surface shape glass plate
is cut into a desired external form, and the surface of the glass
plate is polished. Thus, the curved surface shape protective glass
10 such as a dome-shaped protective glass 10 having a desired shape
and a desired surface roughness is obtained.
The method for obtaining the curved surface shape protective glass
10 is not limited to bending, and is obtained by, for example,
cutting of a thick glass plate.
The protective glass 10 may further have a water-repellent film
(not shown) on the main surface thereof. Material of the
water-repellent film is specifically a material having high water
repellency, and is preferably a material further having an
antifouling property. Examples of such materials of the
water-repellent film include a fluorine-containing organic material
and a fluorine resin, and more preferably include a
fluorine-containing organic silicon compound and a
fluorine-containing organic compound having hydrolyzability.
Thickness of the water-repellent film is not particularly limited
so long as transmitting property of the protective glass 10 is not
impaired. For example, when the thickness is 10 nm or more, the
effect of water repellency can be exhibited, and this is preferred.
The thickness is more preferably 100 nm or more. The upper limit of
the thickness of the water-repellent film is not particularly
limited, but is preferably 1 .mu.m or less from the standpoint of
productivity.
The protective glass 10 is preferably constituted of a glass having
high transparency. A multicomponent oxide glass can be used as a
material of a glass used as the protective glass 10.
Specific examples of the composition of the glass used as the
protective glass 10 are shown below, but the composition of the
glass is not limited to those. The glass used in the present
invention is not particularly limited so long as it contains
sodium, and glasses having various compositions can be used so long
as the glasses contain a composition that can be molded and
strengthened by a chemical strengthening treatment or a physical
strengthening treatment.
Specifically, examples of the glass include aluminosilicate glass,
soda lime glass, borosilicate glass, lead glass, alkali barium
glass, aluminoborosilicate glass, glass ceramics and
alkali-containing optical glass. Of those, glass ceramics has
relatively high strength. Therefore, when the glass ceramics is
subjected to a physical strengthening treatment or a chemical
strengthening treatment, a strengthened glass having higher
strength is easily obtained.
Glass ceramics is that crystals are precipitated in a glass. As
compared with an amorphous glass free of crystal, the glass
ceramics is hard and difficult to be scratched. Furthermore, when
the glass ceramics are subjected to an ion-exchange treatment to be
chemically strengthened, strength can be further enhanced.
The glass ceramics can be obtained by heat-treating an amorphous
glass under appropriate conditions. For example, glass ceramics
having visible light haze value of 1.0% or less in terms of 0.8 mm
thickness is useful as the protective glass 10. The haze value can
be measured, for example, using illuminant C that is the standard
of standard illuminant defined in CIE, using a haze meter "HZ-2"
manufactured by Suga Test Instruments Co., Ltd.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 56 to 66%, Al.sub.2O.sub.3: from 8 to 18%, Na.sub.2O: from 9
to 17%, K.sub.2O: from 1 to 11%, MgO: from 2 to 12%, CaO: from 0 to
5%, SrO: from 0 to 5%, BaO: from 0 to 5% and ZrO.sub.2: from 0 to
5%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 58 to 65%, Al.sub.2O.sub.3: from 14 to 21%, Na.sub.2O: from 12
to 19%, MgO: from 3 to 10%, K.sub.2O: from 0.5 to 1.3%, ZrO.sub.2:
from 0.1 to 0.5% and TiO.sub.2: from 0.0 to 0.1%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 55 to 65%, Al.sub.2O.sub.3: from 12 to 22%, Na.sub.2O: from 10
to 20%, K.sub.2O: from 0 to 2%, MgO: from 1 to 9% and ZrO.sub.2:
from 0 to 5%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 55 to 65%, Al.sub.2O.sub.3: from 12 to 22%, Na.sub.2O: from 10
to 20%, K.sub.2O: from 0 to 2%, MgO: from 1 to 9%, ZrO.sub.2: from
0 to 1% and TiO.sub.2: from 0 to 1%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 60 to 70%, Al.sub.2O.sub.3: from 9 to 19%, Na.sub.2O: from 9
to 19%, K.sub.2O: from 0 to 4%, MgO: from 3 to 6%, CaO: from 0 to
1% and ZrO.sub.2: from 0 to 1%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 45 to 70%, B.sub.2O.sub.3: from 1 to 9%, Al.sub.2O.sub.3: from
15 to 25%, Na.sub.2O: from 7 to 18%, K.sub.2O: from 0 to 1%, MgO:
from 0 to 5%, CaO: from 0 to 1% and TiO.sub.2: from 0 to 1%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 45 to 70%, B.sub.2O.sub.3: from 1 to 9%, Al.sub.2O.sub.3: from
15 to 25%, Na.sub.2O: from 7 to 18%, K.sub.2O: from 0 to 1%, MgO:
from 0 to 5%, CaO: from 0 to 1% and SnO.sub.2: from 0 to 1%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 50 to 80%, Al.sub.2O.sub.3: from 1 to 30%, B.sub.2O.sub.3:
from 0 to 6%, P.sub.2O.sub.5: from 0 to 6%, Li.sub.2O: from 0 to
20%, Na.sub.2O: from 0 to 20%, K.sub.2O: from 0 to 10%, MgO: from 0
to 20%, CaO: from 0 to 20%, SrO: from 0 to 20%, BaO: from 0 to 15%,
ZnO: from 0 to 10%, TiO.sub.2: from 0 to 5% and ZrO.sub.2: from 0
to 8%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 65 to 75%, Al.sub.2O.sub.3: from 1 to 5%, Na.sub.2O: from 7 to
17%, K.sub.2O: from 0 to 1%, MgO: from 3 to 6% and CaO: from 6 to
9%.
One example of the composition of the glass used as the protective
glass 10 contains, in mass percentage on oxide basis, SiO.sub.2:
from 65 to 75%, Al.sub.2O.sub.3: from 3 to 10%, Na.sub.2O: from 7
to 17%, K.sub.2O: from 0 to 1%, MgO: from 3 to 6%, CaO: from 6 to
9% and ZrO.sub.2 as a trace component: from 0 to 1%.
Composition range of each component in the glass composition of the
protective glass 10 of this embodiment having the above-described
components and other optional components are described below. The
unit of content in each composition is mass percentage or mass ppm,
on oxide basis and is simply represented by "%" and "ppm",
respectively.
SiO.sub.2 is a main component of the glass. The SiO.sub.2 content
is preferably 45% or more, more preferably 55% and still more
preferably 60% or more in order to maintain weather resistance of
the glass and prevent devitrification.
On the other hand, the SiO.sub.2 content is preferably 80% or less
and more preferably 70% or less in order to facilitate melting and
enhance foam quality.
Al.sub.2O.sub.3 is an essential component for improving weather
resistance of the glass. In the glass of this embodiment, the
Al.sub.2O.sub.3 content is preferably 7% or more and more
preferably 10% or more in order to maintain practically necessary
weather resistance.
The Al.sub.2O.sub.3 content is preferably 30% or less, more
preferably 23% or less and still more preferably 20% or less in
order to enhance optical properties and enhance foam quality.
B.sub.2O.sub.3 is a component accelerating melting of glass raw
materials and enhancing mechanical properties and weather
resistance. The B.sub.2O.sub.3 content is preferably 6% or less and
more preferably 3% or less in order to prevent the occurrence of
disadvantages such as formation of striae (ream) by volatilization
and corrosion of a furnace wall.
Alkali metal oxides such as Li.sub.2O, Na.sub.2O and K.sub.2O are
components accelerating melting of glass raw materials and
adjusting thermal expansion, viscosity and the like.
The Na.sub.2O content is preferably 8% or more and more preferably
10% or more.
The K.sub.2O content is preferably 3% or less and more preferably
1% or less.
Li.sub.2O is an optional component but facilitates vitrification
and reduces an iron content contained as impurities derived from
raw materials. Therefore, the protective glass 10 of this
embodiment can contain Li.sub.2O in an amount of 2% or less.
The total content of those alkali metal oxides
(Li.sub.2O+Na.sub.2O+K.sub.2O) is preferably from 5 to 20% and more
preferably from 8 to 15% in order to retain clarity when melting
and maintain foam quality of the glass produced.
Alkaline earth metal oxides such as MgO, CaO, SrO and BaO are
components effective to accelerate melting of glass raw materials
and adjust thermal expansion, viscosity and the like.
MgO has a function of decreasing a viscosity when melting a glass
and accelerating melting. MgO further has a function of decreasing
a specific gravity and making it difficult to cause flaws on the
protective glass 10. The MgO content is preferably 10% or less and
more preferably 8% or less in order to decrease a coefficient of
thermal expansion of the glass and prevent devitrification.
CaO is a component accelerating melting of glass raw materials and
adjusting a viscosity, thermal expansion and the like. To achieve
the above functions, the CaO content is preferably 0.5% or more and
more preferably 1% or more. On the other hand, the CaO content is
preferably 6% or less and more preferably 4% or less in order to
prevent devitrification and obtain satisfactory transmitting
property.
SrO has an effect increasing a coefficient of thermal expansion and
decreasing high temperature viscosity of a glass. To achieve the
effect, the protective glass 10 of this embodiment can contain SrO.
The SrO content is preferably 3% or less and more preferably 1% or
less in order to reduce a thermal expansion coefficient of a
glass.
Similar to SrO, BaO has an effect increasing a thermal expansion
coefficient and decreasing high temperature viscosity of a glass.
To achieve the effect, the protective glass 10 of this embodiment
can contain BaO. However, the BaO content is preferably 5% or less
and more preferably 3% or less in order to suppress a thermal
expansion coefficient of a glass low.
The total content of those alkaline earth metal oxides
(MgO+CaO+SrO+BaO) is preferably from 1 to 15% and more preferably
from 3 to 10% in order to reduce a coefficient of thermal
expansion, prevent devitrification and maintain strength.
In the composition of the protective glass 10 of this embodiment,
ZrO.sub.2 may be contained as an optional component in an amount of
preferably 10% or less and more preferably 5% or less in order to
enhance heat resistance and surface hardness of a glass. When the
ZrO.sub.2 content is 10% or less, the glass is difficult to
devitrify.
The protective glass 10 of this embodiment may contain SO.sub.3 as
a refining agent. In this case, the SO.sub.3 content is, in mass
percentage, preferably more than 0% and less than 0.5%. The
SO.sub.3 content is more preferably 0.4% or less, still more
preferably 0.3% or less and still further preferably 0.25% or
less.
The protective glass 10 of this embodiment may contain at least one
of Sb.sub.2O.sub.3, SnO.sub.2 and As.sub.2O.sub.3 as an oxidizing
agent and a fining agent. In this case, each content of
Sb.sub.2O.sub.3, SnO.sub.2 and As.sub.2O.sub.3 is, in mass
percentage, preferably from 0 to 0.5%. Each content is more
preferably 0.2% or less and still more preferably 0.1% or less.
Sill further preferably, those are not substantially contained.
The protective glass 10 of this embodiment may contain NiO. When
NiO is contained, NiO further functions as a coloring component.
Therefore, the NiO content is preferably 10 ppm or less based on
the total amount of the glass composition.
The protective glass 10 of this embodiment may contain
Cr.sub.2O.sub.3. When Cr.sub.2O.sub.3 is contained, Cr.sub.2O.sub.3
further functions as a coloring component. Therefore, the
Cr.sub.2O.sub.3 content is preferably 10 ppm or less based on the
total amount of the glass composition.
The protective glass 10 of this embodiment may contain MnO.sub.2.
When MnO.sub.2 is contained, MnO.sub.2 further functions as a
visible light-absorbing component. Therefore, the MnO.sub.2 content
is preferably 50 ppm or less based on the total amount of the glass
composition.
The protective glass 10 of this embodiment may contain TiO.sub.2.
When TiO.sub.2 is contained, TiO.sub.2 further functions as a
visible light-absorbing component. Therefore, the TiO.sub.2 content
is preferably 1000 ppm or less based on the total amount of the
glass composition.
The protective glass 10 of this embodiment may contain at least one
component selected from the group consisting of CoO, V.sub.2O.sub.5
and CuO. When those components are contained, those components
further function as a visible light-absorbing component, thereby
decreasing visible light transmittance. Therefore, the content of
those components is preferably 10 ppm or less based on the total
amount of the glass composition.
<Chemical Strengthening Treatment>
The chemical strengthening treatment is conducted by immersing a
glass containing sodium in a molten salt containing specific salt
or base and having a temperature equal to or lower than a glass
transition temperature, thereby ion-exchanging sodium ions with
potassium ions having larger atomic radius. When a glass containing
lithium is chemically strengthened, the chemical strengthening
treatment conducted by ion-exchanging lithium ions with sodium ions
having larger atomic radius. In the case of the glass containing
both sodium and lithium, the chemical strengthening treatment may
include two treatments of a treatment of ion-exchanging sodium ions
with potassium ions and ion-exchanging lithium ions with sodium
ions.
The chemical strengthening step is, for example, a step of bringing
a glass containing sodium into contact with an inorganic salt
containing at least one salt or base selected from the group
consisting of potassium nitrate, sodium nitrate, K.sub.2CO.sub.3,
Na.sub.2CO.sub.3, KHCO.sub.3, NaHCO.sub.3, K.sub.3PO.sub.4,
Na.sub.3PO.sub.4, K.sub.2SO.sub.4, Na.sub.2SO.sub.4, KOH and NaOH
to conduct ion-exchange between Na ions in the glass and K ions in
the inorganic salt, thereby forming a compressive stress layer in
the glass surface.
In the chemically strengthened glass obtained by the chemical
strengthening treatment, a stress profile formed (a vertical axis
is a compressive stress value (CS) and a horizontal axis is a depth
of a compressive stress layer (DOL)) changes by controlling time
and temperature of the ion exchange, a salt used and other
treatment conditions. For example, in the case where a stress value
of the chemically strengthened glass, obtained by conducting an ion
exchange treatment of ion-exchanging lithium ions with sodium ions
and an ion exchange treatment of ion-exchanging sodium ions with
potassium ions to one glass, is measured, the stress profile draws
a bent profile having different inclination with the bending point
as a boundary. In other words, when the combination of ion-exchange
to the glass is two or more groups and two or more kinds of ions in
the glass are ion-exchanged, a depth of the compressive stress
layer can be increased while increasing the surface compressive
stress value, and a high strength chemically strengthened glass is
obtained. Examples of the ion-exchange method include a method of
immersing a glass in a molten salt containing two kinds of ions and
a method of immersing a glass in multistage using different two or
more kinds of molten salts. Thus, a stress profile in which the
bending point is present as described above is obtained by passing
through a process giving two or more groups of the combination of
ion-exchanges.
When the surface of a glass is ion-exchanged and a surface layer
having compressive stress remained therein is formed, compressive
stress remains in the surface of a glass and strength of the glass
is enhanced. The strengthened glass obtained changes depending on a
thickness of a glass and its composition, and is appropriately
designed so as to be surely strengthened depending on uses of the
glass.
The chemical strengthening treatment is preferably conducted at a
temperature in a range of from 300 to 500.degree. C. from the
standpoint of preventing change in quality (weathering) due to
elution of an alkali in the chemically strengthened glass obtained
by the chemical strengthening treatment. A salt such as hydrogen
sulfate having the effect of preventing elution of an alkali may be
added to a molten salt.
The thickness t of the chemically strengthened glass according to
this embodiment contributes to reduction in weight, and therefore
is generally 3.5 mm or less and preferably 2.5 mm or less. The
thickness t is more preferably 2.0 mm or less, still more
preferably 1.7 mm or less, still further preferably 1.5 mm or less,
still further preferably 1.3 mm or less and particularly preferably
1.0 mm or less. The glass having the thickness t of less than 0.5
mm is easy to be broken. Therefore, the thickness t is preferably
0.5 mm or more.
The chemically strengthened glass according to this embodiment has
a compressive stress layer in the surface thereof by the
ion-exchange treatment. When a surface compressive stress value is
high, the glass is difficult to be broken by curved mode. For this
reason, the surface compressive stress value of the chemically
strengthened glass is preferably 200 MPa or more, and more
preferably 400 MPa or more, 600 MPa or more, 800 MPa or more, 900
MPa or more, 1000 MPa or more and 1100 MPa or more, in this
order.
In the case where flaws having a depth exceeding the value of a
depth of the compressive stress layer (DOL) are formed during the
use of the chemically strengthened glass, breakage of the
chemically strengthened glass is easy to occur. For this reason,
the DOL of the chemically strengthened glass is preferably large.
The DOL is preferably 10 .mu.m or more, and more preferably 40
.mu.m or more, 60 .mu.m or more, 70 .mu.m or more, 80 .mu.m or
more, 90 .mu.m or more, 100 .mu.m or more, 110 .mu.m or more, 120
.mu.m or more, 130 .mu.m or more, 140 .mu.m or more, 150 .mu.m or
more, 200 .mu.m or more, 300 .mu.m or more, 400 .mu.m or more, 500
.mu.m or more and 550 .mu.m or more, in this order.
In particular, in the chemically strengthened glass used in the
protective glass of this embodiment, when the combination of the
thickness t and the DOL is a combination of thickness t being in a
range of from 1.5 to 3.5 mm and the DOL being in a range of from
200 to 580 .mu.m, the chemically strengthened glass is difficult to
be broken even in outdoor environment, and this is preferred. The
combination of the thickness t and the DOL is preferably a
combination of the thickness t being in a range of from 1.8 to 3.5
mm and the DOL being in a range 250 to 580 .mu.m and more
preferably a combination of the thickness t being in a range of
from 2.0 to 3.5 mm and the DOL being in a range of from 300 to 580
.mu.m.
In the chemically strengthened glass used for the protective glass
of this embodiment, in addition to the relationship between the
thickness t and the DOL, the surface compressive stress value is
preferably 700 MPa or more, more preferably 800 MPa or more and
still more preferably 900 MPa or more.
In the chemically strengthened glass used for the protective glass
of this embodiment, in addition to the relationship among the
thickness t, the DOL and the surface compressive stress value, the
compressive stress value at a depth of 100 .mu.m from the surface
is preferably 100 MPa or more and more preferably 105 MPa or
more.
In the case where the strengthened glass is a physically
strengthened glass, similar to the above, the surface compressive
stress value and the depth of compressive stress are preferably the
above ranges. In the case where the glass is physically
strengthened, the temperature conditions are set such that the
glass surface is cooled rapidly and the temperature inside the
glass is gradually decreased, thereby obtaining a (physically)
strengthened glass. In this case, the glass surface returns to room
temperature in an elongated state and the inside of the glass
gradually shrinks. As a result, a compressive stress layer is
generated in the surface and tensile stress is generated in the
inside of the glass. The characteristics of the physically
strengthened glass are that the surface compressive stress is small
but compressive stress is deeply present. For example, the surface
compressive stress value is about 200 MPa and the depth of the
compressive stress layer is 100 .mu.m or more. Furthermore, for
example, the surface compressive stress value may be from about 100
to 150 MPa and the depth of the compressive stress layer may be
from 1/5 to 1/6 of the thickness of the glass.
The chemically strengthened glass preferably has at least one
bending point in a region forming the compressive stress layer when
a stress profile of vertical axis: CS and horizontal axis: DOL is
given. When the chemically strengthened glass has a stress
distribution curve having different inclination with the bending
point as a boundary, the compressive stress layer enters deeply and
the glass is difficult to be broken, which is preferred. As a
result, the chemically strengthened glass exhibits the effect of
preventing cracking of the protective glass by stepping stone and
the like.
As for the strength of the chemically strengthened glass and
physically strengthened glass obtained, evaluation index by
stepping stone described before can be applied. Specifically, the
strength can be evaluated based on SAE J400, JASO M104 and ISO
20567-1. For example, strength can be evaluated by confirming a
cracked state when granite (gravel) having a size of from 9 to 15
mm as an emanation is ejected to a strengthened glass (including a
dome shape) under 0.1 MPa, 0.2 MPa or 0.4 MPa based on the
conditions of JASO M104.
Surface roughness (Ra) of the protective glass 10 can be
appropriately set. For example, the surface roughness of the
protective glass 10 is preferably 100 nm or less, more preferably
70 nm or less and still more preferably 50 nm or less.
The protective glass 10 may have a structure in which a vibrator 40
is arranged such that the protective glass itself vibrates (see (a)
of FIG. 4 and (b) of FIG. 4). When the protective glass 10 is
provided with the vibrator 40, the protective member 1 may be
provided with or may not be provided with the sensor 20. The
vibrator 40 may be directly mounted on the protective glass 10 or
may be mounted on the support part 2. The protective glass 10 may
have a vibration suppression function detecting vibration frequency
and suppressing vibration. By this function, vibration damping of
the protective glass 10 is prevented and given vibration frequency
can be maintained. The vibrator 40 may be a piezoelectric element
or may be an element oscillating with stable vibration frequency,
such as an electromagnetic actuator, a piezo element, a crystal
vibrator, a ceramic oscillator or a magnetostrictor. Thus, when the
vibrator 40 vibrates, the protective glass functions as a speaker,
and when mounted on a car, vibration during running can be
suppressed. Furthermore, as described later, strains attached to
the protective glass 10 can be removed.
<Sensor 20>
The sensor 20 accommodated has detecting function or sensing
function using millimeter waves, ultrasonic waves, laser, visible
light, infrared light or LIDAR or comprehensively using those and
can be used as a non-contact sensor of a light detection method, an
ultrasonic method, a microwave method, a laser method, a radiation
method or an image discrimination method. For example, when the
sensor 20 is mounted on a car, a distance to an adjacent vehicle
approaching the car and an obstacle present in running direction
can be measured using the detecting function. Furthermore, an
external arrangement mechanism may be driven through a
communication equipment arranged outside based on a signal
transmitted by the sensor 20. For example, when the communication
equipment is a transducer arranged on a windshield, a wiper can be
driven and a heater can be operated, through the transducer.
The sensor 20 may be an ultrasonic sensor. Ultrasonic waves are
utilized for the measurement of a distance and for water repellency
and cleaning of a window, and always stable visibility and
instrument display are obtained. In particular, when the sensor 20
is mounted on a car, the sensor can be applied to antifogging and
snow melt by utilizing its characteristics.
When the sensor 20 is an ultrasonic sensor, it is known that
ultrasonic waves are attenuated as frequency band of ultrasonic
waves transmitted and received is high. For this reason, ultrasonic
waves of frequency band lower than 100 KHz, such as from 1 KHz to
20 KHz or from 40 KHz to 60 KHz, are actually utilized.
<Camera 30>
One or a plurality of camera 30 is present depending on its uses.
For example, when the camera 30 is mounted on means of
transportation, such as a car or an electric train, or a mobile
equipment such as a drone, a plurality of cameras may be arranged
by use, such as for close range monitoring, forward monitoring and
rear monitoring. Furthermore, an image and a video of approaching
person and obstacle can be obtained by using the camera in
combination with the detection function or the sensing function by
the sensor 20.
<Mounting Part 5>
FIG. 2 is a side view showing one example of sensor configuration
in this embodiment. The mounting part 5 is constituted of the
sensor, the camera 30 and a connecting part connecting those. Power
supply of the mounting part 5 may be wired power supply (see (a) of
FIG. 3) and may be wireless power supply by external communication
means using a sensor terminal (see (b) of FIG. 3). A plurality of
sensors can be mounted by electrical conduction by the powder
supply mechanism of the mounting part 5. In the connecting part
connecting the sensor or camera 30, a lead wire and may be used in
the base member 15, a conductive material may be used for forming
the connecting part.
The mounting part is arranged on the base member 15. Material of
the base member 15 may be silicon or glass, and other than those,
may be a metal such as iron or aluminum. Alternatively, a
conductive material may be laid between the base member 15 and the
mounting part. For example, when an ultrasonic sensor is mounted, a
vibrator has, for example, an ultrasonic generating element 50 and
is fitted in the mounting part 5 such that the ultrasonic
generating element 50 does not expose outside. In this case, a
material such as aluminum, glass, polyimide, silicon or
polycarbonate can be used for the vibrator.
<Driving Principle>
The ultrasonic generating element 50 as shown in FIG. 2 generally
utilizes a principle of applying high frequency voltage to a
piezoelectric element to vibrate the piezoelectric element.
Ultrasonic waves generated by applying high frequency voltage to a
piezoelectric element to vibrate the piezoelectric element is
transmitted to a target object to be measured and received as
reflected waves reflected by the object to be measured. As a
result, for example, a distance to an approaching adjacent vehicle
or an obstacle present in a running direction can be measured. The
ultrasonic generating element 50 is provided with a transmitting
part intermittently transmitting pulse signals and a receiving part
receiving its reflected waves and therefore functions as a
sensor.
The ultrasonic generating element 50 may utilizes a principle that
a heating element is driven by applying an electric current that
changes in an ultrasonic cycle to the heating element from a power
supply and as a result, a calorific value by the heating element
follows the frequency of an electric current and periodically
changes. The periodical heat generated by the heating element is
transmitted to the vibrator and the temperature of the vibrator
periodically changes. The vibrator repeats thermal expansion and
contraction periodically in a thickness direction depending on its
temperature and vibrates. Ultrasonic waves are generated from a
vibrating surface of the vibrator by the vibration. For the heating
element, an electrical resistor generating Joule heat, such as
aluminum may be used and Peltier element may be used.
The ultrasonic generating element 50 can detect reflected waves
(from an obstacle or the like) using the receiving part equipped
with a piezoelectric vibration detecting element. For example, the
piezoelectric vibration detecting element can be prepared on SOI
substrate by MEMS technology and is formed by laminating so as to
sandwich a piezoelectric thin film between a top electrode and a
bottom electrode. The piezoelectric thin film is, for example, lead
zirconate titanate (PZT), and the piezoelectric vibration detecting
element converts a displacement of the vibrating part adjacently
arranged into an electrical signal and detects ultrasonic
waves.
The piezoelectric vibration detecting element performs arithmetic
processing based on an electric signal output into a circuit
element to conduct amplification of a signal and removal of noises,
and compares phase difference and time difference between
ultrasonic waves transmitted from the transmitting part and
ultrasonic waves detected. The vibrator is a piezoelectric element
or may be an element stably oscillating vibration frequency, such
as an electromagnetic actuator, a piezo element, a crystal
vibrator, a ceramic oscillator or a magnetostrictor.
As the effect synergistically obtained, water droplets and stains
attached to the protective glass can be removed by mounting the
ultrasonic generating element 50 as a sensor and irradiating the
protective glass with ultrasonic waves.
By the above, a sensor module equipped with a protective member,
having both properties of various sensor functions such as
detection of a distance and removal of stains and the chemically
strengthened glass having high rigidity is provided.
EXAMPLES
The present invention is described below based on specific
examples, but the invention is not construed as being limited to
the following examples.
Examples 1 to 5 and Comparative Examples 1 to 4
Large-sized plate glasses A to E having a thickness of 0.5 mm
consisting of aluminosilicate glass manufactured by a float process
were prepared. Those aluminosilicate glasses had the following
compositions in mass percentage on oxide basis.
Glass A: SiO.sub.2: 60.9%, Al.sub.2O.sub.3: 12.8%, Na.sub.2O:
12.2%, K.sub.2O: 5.9%, MgO: 6.7%, CaO: 0.1%, SrO: 0.2%, BaO: 0.2%
and ZrO.sub.2: 0.1%
Glass B: SiO.sub.2: 60.9%, Al.sub.2O.sub.3: 16.8%, Na.sub.2O:
15.6%, MgO: 5.3%, K.sub.2O: 1.2%, ZrO.sub.2: 0.3% and TiO.sub.2:
0.1%
Glass C: SiO.sub.2: 71.6%, Al.sub.2O.sub.3: 1.9%, Na.sub.2O: 13.4%,
K.sub.2O: 0.3%, MgO: 4.7%, CaO: 7.8% and ZrO.sub.2: 0.2%
Glass D: SiO.sub.2: 59.9%, B.sub.2O.sub.3: 7.7%, Al.sub.2O.sub.3:
17.2%, MgO: 3.3%, CaO: 4.1%, SrO: 7.7% and BaO: 0.1%
Glass E: SiO.sub.2: 69.6%, Al.sub.2O.sub.3: 12.6%, Li.sub.2O: 3.9%,
Na.sub.2O: 5.4%, K.sub.2O: 1.6%, MgO: 4.7%, CaO: 0.2% and
ZrO.sub.2: 2.0%
Subsequently, protective members of Examples 1 to 5 and Comparative
Examples 1 to 3 were produced from the glasses A to E through (1)
plate glass cutting step, (2) machining step, (3) polishing step,
(4-1) chemical strengthening step or (4-2) physical strengthening
step and (5) laminating step shown below. Glass material used in
each example is shown in Table 1. Glass plates having desired
thickness were manufactured by adjusting tensile speed of a glass
when producing a glass and conducting polishing and etching as
necessary.
The protective member of Comparative Example 4 was produced using a
resin in place of a glass.
(1) Plate Glass Cutting Step
The plate glass was cut into a given size using a diamond
blade.
(2) Machining Step
Subsequently, the end surface of the glass cut was subjected to
machining.
(3) Polishing Step
The glass subjected machining was mirror-polished. By this, a glass
having surface roughness Ra of a main surface of 100 nm or less was
formed.
(4-1) Chemical Strengthening Step
Examples 1 to 3
A molten salt of potassium nitrate (KNO.sub.3) was heated to
430.degree. C., and the glass subjected to the polishing step was
immersed in the molten salt for 5 hours in Examples 1 and 3 and for
7 hours in Example 2 to perform a chemical strengthening treatment.
After the chemical strengthening treatment, the glass was washed
with ion-exchanged water at from 50 to 90.degree. C. two times,
washed with a running ion-exchanged water of room temperature and
then dried at 60.degree. C. for 2 hours.
Example 4
In Example 4, the chemical strengthening treatment was conducted in
two stages. Specifically, the glass E subjected to the polishing
step was immersed in a molten salt consisting of 100% NaNO.sub.3
heated to 450.degree. C., for 2.5 hours. After cleaning, the glass
was immersed in a molten salt consisting of 100% KNO.sub.3 heated
to 425.degree. C., for 1.5 hours, followed by cleaning. Thus, a
chemically strengthened glass was obtained. Those cleanings were
conducted in the same manner as in Examples 1 to 3.
(4-2) Physical Strengthening Step
Example 5
The glass C subjected to the polishing step was maintained in an
electric furnace at a rapid cooling initiation temperature (the
vicinity of a softening temperature) for 5 minutes, taken out of
the electric furnace and allowed to cool in the atmosphere, thereby
performing physical strengthening.
(5) Laminating Step
After the chemical strengthening treatment or physical
strengthening treatment, the plate glass obtained was laminated to
a cylindrical support part made of a glass with an adhesive layer.
Thus, protective members of Examples 1 to 5 and Comparative
Examples 1 to 4 were prepared.
Evaluation Step
Evaluation of the protective member (glass or resin) of each
example was conducted by the following analytical method.
In the evaluation of transmittance of the protective member,
transmission spectrum in a wavelength region of from 300 to 1000 nm
was measured using a spectrophotometer (U-4100 manufactured by
Hitachi High-Technologies Corporation). The minimum value Tmin in a
wavelength region of from 400 to 800 nm was calculated.
Surface compressive stress value (CS) and depth of compressive
stress layer (DOL) of the strengthened glass were measured using a
glass surface stress meter FSM-6000 or SLP-1000 manufactured by
Orihara Industrial Co., Ltd.
TABLE-US-00001 TABLE 1 Chemical strengthening conditions (First
stage) (Second stage) Surface Depth of Chemical Chemical
compressive compressive strengthening strengthening Glass Thickness
stress CS stress layer DOL Example Strengthening Molten salt
Temp/time Molten salt Temp/time material (mm) (MPa) (.mu.m) Ex. 1
Chemical KNO.sub.3 430.degree. C. -- -- Glass A 1.0 700 45
strengthening 100 wt% 5 hours Ex. 2 KNO.sub.3 430.degree. C. -- --
Glass B 1.0 1100 45 100 wt% 7 hours Ex. 3 KNO.sub.3 430.degree. C.
-- -- Glass C 1.0 600 10 100 wt% 5 hours Ex. 4 NaNO.sub.3
450.degree. C. KNO.sub.3 425.degree. C. Glass E 1.0 800 150 100 wt%
2.5 hours 100 wt% 1.5 hours Ex. 5 Physical -- -- -- -- Glass C 3.0
110 500 strengthening Comparative Non- -- -- -- -- Glass A 1.0 --
-- Ex. 1 strengthening Comparative -- -- -- -- Glass B 1.0 -- --
Ex. 2 Comparative -- -- -- -- Glass D 1.0 -- -- Ex. 3 Comparative
-- -- -- -- Resin 2.0 -- -- Ex. 4 Rigidity evaluation (stepping
stone Light Light Removal of Crack Heat resistance Comprehensive
Example test result) transmittance resistance water droplets
resistance evaluation evaluation Ex. 1 .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle- . .smallcircle.
.smallcircle. Ex. 2 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircle- . .smallcircle. .smallcircle. Ex. 3
.DELTA. .smallcircle. .smallcircle. .smallcircle. .smallcircle.
.sma- llcircle. .smallcircle. Ex. 4 .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle- . .smallcircle.
.smallcircle. Ex. 5 .DELTA. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .sma- llcircle. .smallcircle.
Comparative x .smallcircle. .smallcircle. .smallcircle. x
.smallcircle. x Ex. 1 Comparative x .smallcircle. .smallcircle.
.smallcircle. x .smallcircle. x Ex. 2 Comparative x .smallcircle.
.smallcircle. .smallcircle. x .smallcircle. x Ex. 3 Comparative x
.smallcircle. x .smallcircle. x x x Ex. 4
Evaluation results evaluating rigidity, light transmitting
property, weather resistance, removal of water droplets by
ultrasonic irradiation, cracking of glass by ultrasonic irradiation
and heat resistance to the protective member of each example are
shown in Table 1. For example, rigidity evaluation of
".smallcircle." shows that the protective member has sufficient
rigidity necessary in the case of arranging outdoors a sensor
module equipped with the protective member and ".DELTA." shows that
the protective member does not satisfy necessary rigidity in a part
of the results. ".times." shows that necessary rigidity is not
satisfied in all cases.
1. Rigidity Evaluation (Stepping Stone Test Result)
Rigidity evaluation (stepping stone test) was carried out to the
protective member of each example. Deformation amount of a
protective material when a certain force is applied is required to
be small in order to protect a sensor and in order that the
internal sensor maintains certain sensing function. The rigidity
evaluation was conducted based on the conditions of JASO M104.
Specifically, granite (gravel) having a size of from 9 to 15 mm as
an emanation was ejected at an angle of 90.degree. in an ejection
distance of 350 mm three times. The test was conducted changing an
ejection pressure, and the rigidity was evaluated as follows. The
case where the protective member was broken by the ejection
pressure of 0.1 MPa was evaluated as "x", the case where the
protective member was not broken by the ejection pressure of 0.1
MPa but was broken by the ejection pressure of 0.2 MPa was
evaluated as ".DELTA.", the case where the he protective member was
not broken by the ejection pressure of 0.2 MPa but was broken by
the ejection pressure of 0.4 MPa was evaluated as ".smallcircle.",
and the case where the protective member was not broken by the
ejection pressure of 0.4 MPa was evaluated as
".smallcircle..smallcircle.". The results are shown in Table 1.
2. Crack Evaluation
The protective material is required to be not broken when
deformation is applied to the protective material. Ring-on-ring
test was conducted to the protective member of each example using a
jig having upper ring: 10 mm and lower ring: 30 mm by an autograph
manufactured by Shimadzu Corporation. The protective member of each
example was processed into a sample having a size of 50 mm.times.50
mm.times.1 mm. The case where the sample was broken when 600 MPa or
more of tensile stress was applied was indicated as
".smallcircle.", and the case where the sample was broken when less
than 600 MPa of tensile stress was applied was indicated as "x".
The resin (Comparative Example 4) was not broken, but deformation
amount was large and there was a concern of bringing into contact
with an internal sensor when force was applied. For this reason,
the resin was evaluated as "x". As a result, it was understood that
the glasses subjected to the strengthening treatment of Examples 1
to 5 had rigidity and crack resistance necessary for protecting the
sensor. On the other hand, it was understood that the glasses not
subjected to the strengthening treatment (Comparative Examples 1 to
3) and the resin (Comparative Example 4) did not have sufficient
rigidity and crack resistance.
3. Light Transmittance
Transmission spectrum in a wavelength region of from 400 to 800 nm
of the protective member of each example was measured. In a sample
having a size of 50 mm.times.50 mm.times.1 mm obtained by
processing the protective member of each example, the sample having
Tmin of 85% or more was evaluated as ".smallcircle." and a sample
having Tmin of less than 85% was evaluated as "x" As a result, it
could be confirmed that regardless of the presence or absence of
the strengthening treatment, each glass and the resin cover showed
good results.
4. Weather Resistance
Resistance (weather resistance) to weathering and heat shock when a
sensor module equipped with the protective member of each example
was arranged outdoors was evaluated by the following tests.
The evaluation of weather resistance was conducted by both a test
holding the protective member of each example at a temperature of
60.degree. C. and a humidity of 80% for 100 hours and thereafter a
test irradiating UV light having a wavelength of 300 nm or less for
10 hours. After conducting those tests, the protective member in
which its surface was slightly cloudy white (weathering) in
appearance was evaluated as ".DELTA.", the protective member
showing no change was evaluated as ".smallcircle." and the
protective member that was deformed and discolored was evaluated as
"x" As a result, it could be confirmed that each glass excluding
the resin cover (Comparative Example 4) showed good results.
5. Removal of Water Droplets
Ultrasonic vibrator was arranged in the protective member of each
example and irradiated with ultrasonic waves, and whether water
droplets attached to the protective member can be removed
(evaluation: .smallcircle.) or cannot be removed (evaluation:
.times.) was evaluated. As a result, the effect of removing water
droplets could be confirmed in all of the protective members, but
cracking occurred in non-strengthened glasses (Comparative Examples
1 to 3). On the other hand, cracking did not occur in the
strengthened glasses (Examples 1 to 5).
6. Heat Resistance Evaluation
Transparent heater was embedded in the protective member of each
example, and after allowing to stand the protective heater at an
elevated temperature for a certain time, its appearance was
evaluated. Specifically, the protective member was held at
100.degree. C. for 1 hour, and the presence or absence of
remarkable deformation and discoloration was then visually
observed. The protective member having deformation and
discoloration is indicated as "x" and the protective member free of
deformation and discoloration is indicated as ".smallcircle.". As a
result, it was understood that the protective members using a glass
of Examples 1 to 5 and Comparative Examples 1 to 3 showed good
results.
Comprehensively judging from the evaluation results of the above 1
to 6, it was understood that the performance of the protective
member strongly depended on a compressive stress value (CS) and a
depth of a compressive stress layer (DOL) after the strengthening
treatment due to the composition of a glass. Furthermore, it was
understood based on the evaluation results obtained that CS and DOL
of the protective glass were preferably DOL being 10 .mu.m or more
and CS being 100 MPa or more, and more preferably DOL being 40
.mu.m or more and CS being 600 MPa or more.
Examples 6 to 10
Protective members of Examples 6 to 10 were produced using glass E
through (1) plate glass cutting step, (2) machining step, (3)
polishing step, (4-1) chemical strengthening step and (5)
laminating step, and were evaluated by 1 to 6 above.
The chemical strengthening treatment in Examples 6, 7 and 10 was
conducted in two stages. Specifically, the glass E after the
polishing step was immersed in a molten salt consisting of 100%
NaNO.sub.3, washed, immersed in a molten salt consisting of 100%
KNO.sub.3, and washed. Thus, a chemically strengthened glass was
obtained. The treatment temperature and time are show in Table
2.
The chemical strengthening treatment in Examples 8 and 9 was
conducted in one stage. Specifically, the glass E after the
polishing step was immersed in a molten salt consisting of 100%
NaNO.sub.3 and washed. Thus, a chemically strengthened glass was
obtained. The treatment temperature and time are show in Table
2.
Examples 11 to 13
Protective members of Examples 11 to 13 were produced using the
glass B through (1) plate glass cutting step, (2) machining step,
(3) polishing step, (4-1) chemical strengthening step and (5)
laminating step, and were evaluated by 1 to 6 above.
The chemical strengthening treatment was conducted in one stage.
Specifically, the glass B after the polishing step was immersed in
a molten salt consisting of KNO.sub.3 and a specific weight ratio
of Na.sub.2NO.sub.3 added thereto, and then washed. Thus, a
chemically strengthened glass was obtained. The weight ratio
between KNO.sub.3 and Na.sub.2NO.sub.3 in the molten salt and the
treatment temperature and time are shown in Table 2.
TABLE-US-00002 TABLE 2 Depth of Chemical strengthening conditions
Compressive stress CS compressive (First stage) (Second stage)
Surface Deep layer Deep Layer stress layer Chemical strengthening
Chemical strengthening Glass Thickness CS 100 .mu.m CS 200 .mu.m CS
DOL Example Molten salt Temp/time Molten salt Temp/time material
(mm) (MPa) (MPa) (MPa) (.mu.m) Ex. 6 NaNO.sub.3: 100 wt%
450.degree. C. KNO.sub.3: 100 wt% 425.degree. C. Glass E 2.0 941 80
7 217 2.5 hours 1.5 hours Ex. 7 NaNO.sub.3: 100 wt% 450.degree. C.
KNO.sub.3: 100 wt% 425.degree. C. 2.0 954 108 43 304 15 hours 1.5
hours Ex. 8 NaNO.sub.3: 100 wt% 450.degree. C. -- -- 2.0 264 119 49
351 24 hours Ex. 9 NaNO.sub.3: 100 wt% 450.degree. C. -- -- 3.2 242
145 85 541 48 hours Ex. 10 NaNO.sub.3: 100 wt% 450.degree. C.
KNO.sub.3: 100 wt% 425.degree. C. 3.2 930 115 70 550 48 hours 1.5
hours Ex. 11 KNO.sub.3: 95 wt% 430.degree. C. -- -- Glass B 2.0 718
92 -- 140 NaNO.sub.3: 5 wt% 96 hours Ex. 12 KNO.sub.3: 95 wt%
430.degree. C. -- -- 2.0 762 -- -- 85 NaNO.sub.3: 5 wt% 24 hours
Ex. 13 KNO.sub.3: 96 wt% 475.degree. C. -- -- 2.0 760 -- -- 41
NaNO.sub.3: 4 wt% 3 hours Rigidity evaluation (stepping stone Light
Weather Removal of Crack Heat resistance Comprehensive Example test
result) transmittance resistance water droplets resistance
evaluation evaluation Ex. 6 .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircl- e. .smallcircle.
.smallcircle. Ex. 7 .smallcircle..smallcircle. .smallcircle.
.smallcircle. .smallcircle- . .smallcircle. .smallcircle.
.smallcircle. Ex. 8 .smallcircle. .smallcircle. .smallcircle.
.smallcircle. .smallcircl- e. .smallcircle. .smallcircle. Ex. 9
.smallcircle..smallcircle. .smallcircle. .smallcircle.
.smallcircle- . .smallcircle. .smallcircle. .smallcircle. Ex. 10
.smallcircle..smallcircle. .smallcircle. .smallcircle. .smallcircl-
e. .smallcircle. .smallcircle. .smallcircle. Ex. 11 .DELTA.
.smallcircle. .smallcircle. .smallcircle. .smallcircle. .s-
mallcircle. .smallcircle. Ex. 12 .DELTA. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .s- mallcircle.
.smallcircle. Ex. 13 .DELTA. .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .s- mallcircle. .smallcircle.
From the results of Table 2, in the protective members (chemically
strengthened glasses) obtained in Examples 6 to 13, cracking did
not occur under at least an ejection pressure of 0.1 MPa based on
JASO M104 in the rigidity evaluation (stepping stone test result).
Furthermore, the desired evaluation result was obtained in each of
light transmittance, light resistance, cracking evaluation and heat
resistance evaluation.
Examples 14 to 16
Flat plate-shaped glass E having a thickness of 6 mm was subjected
to machining to form a dome-shaped glass having an inner radius of
18 mm (inner diameter: 36 mm), an outer radius of 20 mm (outer
diameter: 40 mm) and a thickness (wall thickness) of 2 mm. The
surface of the glass plate after machining was polished. Surface
roughness Ra of the convex surface and concave surface was 8 nm,
and surface roughness Ra of the end surface was 0.15 .mu.m. In this
case, the dome-shaped glass plate was a partially hemispherical
glass having a horizontal width of 25 mm and a height of 5.3 mm.
Thereafter, the partially hemispherical glass was immersed in a
molten salt consisting of 100% NaNO.sub.3, washed, immersed in a
molten salt consisting of 100% KNO.sub.3 and then washed. Thus, the
protective members (partially hemispherical chemically strengthened
glasses) of Examples 14 and 15 were obtained. Protective member
(partially hemispherical chemically strengthened glass) of Example
16 was obtained using the flat plate-shaped glass E having a
thickness of 6 mm in the same manners as above, except for forming
a dome-shaped glass having an inner radius of 16.8 mm (inner
diameter: 33.6 mm), an outer radius of 20 mm (outer diameter: 40
mm) and a thickness (wall thickness) of 3.2 mm. The chemical
strengthening treatment temperature and time are shown in Table 3.
Rigidity of the protective members obtained of Examples 14 to 16
was evaluated.
TABLE-US-00003 TABLE 3 Chemical strengthening conditions (First
stage) (Second stage) Chemical strengthening Chemical strengthening
Thickness Example Molten salt Temp/time Molten salt Temp/time Glass
material (mm) Ex. 14 NaNO.sub.3: 100 wt% 450.degree. C. KNO.sub.3:
100 wt% 425.degree. C. Glass E 2.0 2.5 hours 1.5 hours Ex. 15
NaNO.sub.3: 100 wt% 450.degree. C. KNO.sub.3: 100 wt% 425.degree.
C. 2.0 15 hours 1.5 hours Ex, 16 NaNO.sub.3: 100 wt% 450.degree. C.
KNO.sub.3: 100 wt% 425.degree. C. 3.2 48 hours 1.5 hours
Compressive stress CS Convex surface Concave surface Surface CS of
DOL of convex Depth of Depth of convex surface - surface - Surface
compressive stress Surface compressive stress surface CS of DOL of
concave Rigidity evaluation CS layer DOL CS layer DOL concave
surface surface (stepping stone test Example (MPa) (.mu.m) (MPa)
(.mu.m) (MPa) (.mu.m) result) Ex. 14 946 227 936 207 10 20
.smallcircle. Ex. 15 964 324 944 284 20 40
.smallcircle..smallcircle. Ex. 16 945 590 920 510 25 80
.smallcircle..smallcircle.
From the results of Table 3, the partially hemispherical chemically
strengthened glasses (protective members) obtained in Examples 14
to 16 were that cracking did not occur under at least an ejection
pressure of 0.2 MPa based on JASO M104 in the rigidity evaluation
(stepping stone test result), thus showing high rigidity.
According to this embodiment, a sensor module having excellent
rigidity, scratch resistance and weather resistance and suitable
for outdoor uses can be provided.
Although the preferred embodiment of the present invention is
described in detail below, but the present invention is not
construed as being limited to the above-described specific
embodiments and various modifications or changes can be made in the
range of the gist of the present invention described in the scope
of the claims.
Although the present invention has been described in detail and by
reference to the specific embodiments, it is apparent to one
skilled in the art that various modifications or changes can be
made without departing the spirit and scope of the present
invention. This application is based on Japanese Patent Application
No. 2017-132137 filed Jul. 5, 2017, the disclosure of which is
incorporated herein by reference in its entity.
REFERENCE SIGNS LIST
1: Protective member 2: Support part 5: Mounting part 10:
Protective glass 15: Base member 20: Sensor 25: Power source 30:
Camera 40: Vibrator 50: Ultrasonic generating element 60:
Transparent heater
* * * * *